I imagine there will be several critical "no go" items in terms of serviceability, and a fully operating lift fan is certainly going to be one of them.
A couple of points to remember about that.
The F22 ceased production for several reasons. One of them was certainly associated with cost, and another is to do with very poor availability by modern standards. For comparison, the Rhino has huge availability/reliability built in. An old USN mate of mine told me being programmed to fly on a Rhino squadron meant you were going flying, and as any older fast jet mate will tell you that is often not the case. I hear the Rhino bloke will be flying the aeroplane he is programmed to fly when he expects to fly 98 times in 100 walks. By comparison, my understanding is that the F22 mate is more likely to be back in the crew room 40% of the time...2 in 5 walks! That's not good. Even second and third generation fighters are more available than that.
Availability and reliability have been very high up on the priority list throughout the selection process for the JSF. The aim being that the aeroplanes never fail, and this was driven by the difficulties found with the F22. The F18E/F were the first beneficiaries of the new thinking, and to have been down selected from the initial 3 prototype designs, the F35 is the best in that regard as well. Worrying about lift fan door and variable nozzle serviceability on PPruNe may be conversational, but I am convinced there are some very clever design and operator minds working on those little issues right now, and it is unlikely to be a show stopper at this stage.
NB: people worried about the single engine F16 during the development phase, and made self evident statements like, "But if the engine fails the aeroplane will crash!" With that truism in mind, I have never heard an F16 mate complain about his aeroplane. They all seem to rate it very highly, and having one engine doesn't bother them. Everybody knew its triplex fly-by-wire would be a fatal flaw as well. There are well over 4000 F16s out there now...with their dangerous single engine and their flawed triplex fly-by-wire...and the F35 will replace it. You can bet your very last cent the F35 is going to be a worthy replacement.